Gas turbine shroud with ceramic abradable coatings

Abstract

There is provided a gas turbine shroud including a ceramic abradable coating used as a gap adjusting component that can reduce a fluid leakage from a gap and increase turbine efficiency. A gas turbine ceramic abradable coating includes a bond layer, a thermal barrier ceramic layer, and a porous ceramic abradable layer (hardness may be RC15Y: 80±3). A slit groove is provided in the porous ceramic abradable layer by machining. A width of a rectangular section of the ceramic abradable layer divided by the slit groove may be set to a range of 2 to 7 mm.

1 . A gas turbine shroud, wherein a ceramic abradable coating is placed on a hot gas path surface of the shroud facing a gas turbine moving blade, the ceramic abradable coating being obtained by spraying a bond layer on a substrate, spraying a thermal barrier ceramic layer on the bond layer, spraying an abradable ceramic layer on the thermal barrier ceramic layer, and forming a slit groove in the abradable ceramic layer by machining. 
     
     
         2 . The gas turbine shroud according to  claim 1 , wherein the abradable ceramic layer divided by the slit groove has a rectangular section, and a slit groove width is 0.5 to 2 mm. 
     
     
         3 . The gas turbine shroud according to  claim 1 , wherein the abradable ceramic layer sprayed on the thermal barrier ceramic layer has Rockwell superficial hardness (HR15Y) of 80±3. 
     
     
         4 . A gas turbine comprising a gas turbine shroud according to any one of  claims 1  to  3 . 
     
     
         5 . A method of forming a ceramic abradable coating placed on a hot gas path surface of a shroud facing a gas turbine moving blade, comprising the steps of:
 spraying a bond layer on a substrate; spraying a thermal barrier ceramic layer on the bond layer; spraying an abradable ceramic layer on the thermal barrier ceramic layer; and   forming a slit groove in the abradable ceramic layer by machining.